The gang moved cocaine from South America to Spain, from where it was shipped to Switzerland and Italy, Spanish and Swiss police said in separate statements on Tuesday.
A total of 19 people were arrested as part of an investigation that began in November last year, involving police from Geneva's international airport.
Officers arrested 12 people and seized 800 grammes of cocaine in Switzerland, police said.
A further six people were arrested in Spain, including the 40-year-old Gambia-born alleged gang boss living in Barcelona, and one at Italy's Milan airport, they said.
The cocaine was allegedly transported from South America to Spain.
"Mules" then transported the drugs from Barcelona to points in Switzerland and Italy for sale.
Just over three kilograms (6.6 pounds) of cocaine and computer equipment was seized, police said.